Tow target having combustion signal means



Jan. 13, 1959 O. B. LOLMAUGH ET AL TOW TARGET HAVING COMBUSTION SIGNAL MEANS Filed Sept. 17, 1956 2 Sheets-Sheet 1 Jan. 13, 1959 o. B. LOLMAUGH ET AL 2,869,120

Tow TARGET HAVING coMBusTroN SIGNAL MEANS Filed Sept. 17, 1956 2 Sheets-Sheet 2 ANIM- l j fa? 96) United States TOW TARGET HAVING CUMBUSTION SIGNAL MEANS Orson B. Lolmangh and William E. Thornton, Los Angeles, and Charles A. Smith, Reseda, Calif., assigner-s to Del Mar Engineering Laboratories, Los Angeles, Calif., a corporation Application September 17," 1956, Serial No. 610,066

S Claims. (Cl. 343-18) This invention relates to an aerial tow target for simulating a self-propelled aerial object such as a jet .aircraft for aiording practice in detecting, tracking and intercepting such an object. The invention provides, for example, realistic experience for military personnel in the use of automatic and semi-automatic equipment for fire control and for missile launching control.

One of the problems to which the invention is directed is to provide an identification check to make sure that an object detected in the air is the desired tow target and not some other object such as a manned aircraft. This problem is met by employing a primary detecting means and a corroborating secondary detecting means operating on a different principle. More particularly described, the invention meets this problem by providing a remotely controlled combustion means such as a are on the tow target to be ignited when desired for confirmation detection. Thus, if the primary mode of detecting the tow target is by means of radar, the confirmation may be either by means of infrared detection of the resulting ame or `by Visual observation of the ame, the flame having an exceedingly high rate of radiant energy output in the visible spectrum.

Another problem met by the invention is to provide realistic experience in the use of various target detecting and target tracking devices that depend upon specialized responsiveness to the exhaust stream of a jet or rocket propelled aerial object. It has been found that a relatively small, relatively light and relatively inexpensive tow target may be used for this purpose, the tow target being provided with a flare or rocket means that is capable of simulating a propelling exhaust stream to a satisfactory degree for a brief combustion period, for example, a period of thirty seconds.

While such a combustion period is brief, it is of adequate duration in view of the high speeds of jet aircraft and missiles, since the invention provides for timing the combustion period by remote control to occur at a critical or controlling stage in a countermeasure procedure. In this regard, a further feature of the preferred practice vof the invention is the concept of providing a plurality of such combustion devices for operation in sequence. Thus, a series of such devices may be ignited in succession to provide a prolonged llame period or the successive devices may be ignited at selected stages in a countermeasure procedure, or the successive flares may be ignited for repeated counter-measure exercises in the course of a single target run.

An important feature of the invention is the provision of a built-in safety system to prevent accidental or inadvertent ignition of the ares. The safety system includes normally closed switch means operable by a safety pin when the tow target is on the ground and normally closed switch means that opens automatically whenever the tow target is stored or snubbed on the towing aircraft. p

The features and objects ofthe invention may be under- A. estaras fsftented dan, 13, 1959 stood from the following detailed description considered with the accompanying drawing.

In the drawing, which is to be regarded as merely illustrative:

Figure 1 is a side elevation of the preferred embodiment of a tow target with portions broken away;

Figure 2 is a rear elevation as viewed along the line 2-2 of Figure l;

Figure 3 is a cross-sectional View of the tail n structure showing how an antenna may be incorporated therein; and

Figure 4 is a wiring diagram of the system for remote control of the plurality of combustion means.

The tow target shown in the drawing has a streamlined body, generally designated l0, which may comprise a suitably reinforced thin-walled shell 12 of molded paper. The body 10 is provided with a set of tail vanes 14, and, preferably, the tail vanes have slightly angular tip portions 15 to serve as aerodynamic means for causing the body to rotate about its longitudinal axis for increased stability during flight. The tail vanes 14 may be made of foamed cellular plastic adhesively bonded to the body, and the body may be internally reinforced with the same material. The stream-lined body l0 preferably has an integral rigid'probe or nose member, generally designated llo, that is of slender, tapered configuration and is capableof serving as the sole support for the target body prior to a target run. Thus, the tow plane for the target run may be provided with a launching means for the tow target, as indicated at 17 in Figure l, the launching means being of relatively small cross-sectional dimension and being adapted to telescopically receive the nose probe l5 for support of the tow target until the beginning of a target run.

In the construction shown, the nose probe 16 comprises a thin-walled axial tube 18 of aluminum or the like, the base end of which is attached to a bulkhead member 20 of the body structure and is reinforced by a surrounding ring 22. The .axial tube i3 extends through a second conical reinforcement ring 2li at the leading end of the body l0, and, if desired, the adjacent portion of the body shell may be made of glass fibers impregnated with polyester resin for increased strength. The nose probe lo is adapted yfor attachment to a tow cable Z5, and, preferably, is provided with a rotary joint for this purpose. rThus, a clevis 26 for direct connection to the tow cable may be rotatably mounted in a sleeve 28 at the leading end of the nose probe lo.

lt is contemplated that the tow target body 10 will incorporate suitable radar corner-reflector means to facilitate detection of the tow target by radar, which corner-reflector means may be either monostatic or bistatic. in this instance, the tow target body incorporates a corner-reflector unit that is generally designated by numeral 30.

This reflector unit 30 may include a transverse metal foil sheet 32 sandwiched into a thick transverse wall 34 of'foamed cellular plastic material. A second longitudinal metal foil sheet 35 is sandwiched into a thick longitudinal wall 36 of foamed cellular plastic, and a third metal foil sheet 33 is sandwiched into a third longitudinal wall la of foamed cellular plastic. The three metal foil sheets are in three planes that are perpendicular to each other, and meet at a common center. This corner-reflector unit 3l) spans the interior of the body shell l2 to serve as a reinforcement therefor, and is secured between two spaced reinforcement bulkheads 42 and 44.

The tow target may be provided with any suitable remotely controlled arrangement for the combustion of suitable material to produce a highly heated gaseous stream or a flame for the various purposes of the invention. For example, the tail end of the tow body may incorporate a rearwardly open magazine having a plurality of cylindrical chambers 46 to hold a corresponding plur'ality ofy electrically ignitable rockets or flares 50, each of which iscapable of sustained combustion at a high rate for a period of approximately thirty seconds. The ares 50 are ignited by means including a battery 52 under the control of a radio receiver 5ft.

ln the present arrangement, the battery '52 and the radio receiver 54 are mounted on a housing 55 on the front face of the reinforcement bulkhead 4Z. The housing 55 contains control components that are electrically connected with the magazine 45 by conductors in a cable 56, the cable extending through the radar corner-reflector unit 30. The radio receiver may, for example, operate on a fixed frequency in the range lm tween v200 and 40() megacycles and may be responsive to a particular tone or modulation frequency for control from one or more remote control stations. A remote control station may be on the ground or may comprise a transmitter on an airplane and the airplane may be the tow plane or may be an observation plane.

A feature of the present embodiment of the invention is the utilization ofthe tail lin structure to provide an antenna of substantially larger dimension than the body of the tow target. Such an antenna, which is generally designated by numeral 58 in Figures l and 3, may

comprise two halves of a dipole and, as indicated in Figure 4, may be connected to the radio receiver 54 by means of a sheathed cable, generally designated by numeral 60. Two arms 62 of the antenna are connected to the sheath 65 of the cable and the other two arms 64 are connected to the inner conductor 66 of the cable.

The control system for ignition of the flares may include the components shown in the wiring diagram in Figure 4. When the radio receiver 54 is in operation and receives a radio signal to which it is tuned, it closes a circuit by relay operation for ignition of the flares. This circuit includes a normally closed switch 68 which is connected to the radio receiver by a wire 7d. The normally closed switch 68 is connected by a wire 731 to a rotary solenoid that is represented by a coil 72, the second side of the coil being grounded. The switch 6d is also connected by a wire 74 to a switch arm 75 of a rotary switch, the switch arm 75 being operatively connectedy to the rotary solenoid 72 for actuation thereby as indicated by the dotted line 76. The rotary switch arm 75 is movable step-by-step from a starting position represented by a contact 78 to three contacts $0, till and 82 in sequence.

As indicated in Figure 2, there may be six flares Sil in the magazine 45 to provide three diametrically positioned pairsof flares, lares 1 and 2 to be tired tirst, followed by flares 3 and 4 and, finally flares 5 and 6. In Figure 4, the means for igniting the pair of flares 1 and 2 comprises a corresponding pair of ignitcrs 84, each of which is'connected to the contact S0 at one end and is grounded at the other end. In like manner, a pair of electrical ignitors 85 for ares 3 and 4 is connected to the contact 01,A and a third pair of electrical ignitors 86 for the flares 5 and 6 is connected to the contact 32.

The filament circuit of the radio receiver 54 includes a battery 88 that is grounded inside the radio receiver by a wire 90. During a target run with the target at the end of a tow cable, a filament-energizing circuit is closed by two normally closed switches 92 and '94 in series. These two switches are connected to the battery 8S by a wire 95 and are connected to the filaments of the radio receiver by a wire 96.

.Theswitch 92 is a normally closed switch positioned as indicated in Figure 1 to be opened by contact with the launcher 17 so that the flares may be ignited only whenl the tow target is out of the launcher. The switch 94 is also a normally closed safety switch that operates in unison with the previously mentioned switch 68"'s indicated by the dotted lin`e 98. The two switches 68 v and 94 are opened to keep the flares from being ignited when the tow target is on the ground and away from the launcher. As shown in Figure 1, the two switches 68 and 94 may be opened in unison by insertion ofy a safety pin 100. It is contemplated that the safety pin will be conspicuous and for this purpose a brightly colored ribbon may be added if desired..

When the target is on the ground with the safety pin 100 inserted, the lilament circuit may be closed by a normally open switch 102 which isv connected to the wire 95 by a wire 104 and is connected to ,the wire 96 by a wire 105. This alternate filament-energizing circuit is used whenever a headphone set (not shown) is plugged into the radio receiver for the purpose of tuning the receiver to a test signal. The headphone set is plugged into an audio jack, generally designated 106, and-the normally open switch 102 is operatively connected to the audio jack as indicated by the dotted line 103 to close in response to the insertion of the headphone plug.

The manner in which the invention serves its purpose may be readily understood from the foregoing description. In preparation for a target flight, the magazine 45 is loaded with flares 50, the rotary switch arm 75 is placed at its home position on contact 78, the tow target is engaged with the launcher 17, and the safety pin y100 is withdrawn. As the practice area is approached, the tow target is launched by reeling out the tow cable 25 in preparation for an actual target run.

Whenever ignition of a pair of flares 50 is desired during a target run, a radio signal from a remote control station is sent to the receiver 54, and the output signal thus produced causes momentary energization of the wire 7G; Momentary energization of the wire 70 actuates the rotary solenoid '72 to advance the switch arm y75 one step to the contact S0. The movement of the switch arm 75 to the contact 00 completes a firing circuit through the pair of igniters 84 to initiate combustion in the diametrical pair of ares 1 and 2. The two burning liares produce a high energy incandescent gas streamvthat v may be readily observed over a great distance and that emits infrared radiation for detection by infrared sensing devices.

lf the tow target is to be tracked and intercepted by radar means involving the reflection of lradar signals from the corner-reflector unit 30, a pair of the dares 50 may be ignited for confirmation identification of the target. ln another use of the invention, the dares 50 maybe used to simulate a jet engine .or a rocket for practice ,in the use of infrared responsive devices for detecting, tracking and intercepting aerial targets.

Whenever the tow target is on the ground, lthe safety pin 100 is inserted to open the normally closed safety switches 63 and 94. With the safety pin 100 inserted, the headphone set may be safely plugged into the audio jack 106 for tuning the radio receiver to a test signal. Since the safety v.pin 100 holds the switch 68 open, there is no possibility` of the flares being ignited yby the radio receiver during the tuning procedure.

When the targetis in the launcher, the launcher' holds the normally closed safety switch `92 open Vto prevent energization of the filaments and ythusmalsies it :impossible for the radio receiver to operate for ignition of the flares. ln the final lpreparations for a target yllig'ht', lthe tow target is engaged with the launcher beforelthe safety pin 100 is removed. Thelauncher lthen holds the safety switch 92 open to keep Ithe system inoperative until the tow target is actually launched into the air.

Our description in speciiicdetail of a selected err'ibodi-y mentof the invention will suggest various changes, substitutions and other departures from our disclosure within the spirit and scope of the appended claims.

We claim:

1. An aerial tow target comprising a hollow thinwalled rigid body member having a low drag aerodynamic configuration, the walls of said body member being formed of a non-metallic material permeable by radar waves; means defining a plurality of normally intersecting planes interiorly of said body member and having a metallic surface for reflecting exteriorly propagated radar Waves; a rearwardly directed are magazine mounted to the trailing end of said body member; a plurality of rearwardly directed flares mounted in said magazine; a radio receiver carried within said body member, said radio receiver developing an output signal in response to a received signal from a remote source; and means for igniting said ares in sequence, including means responsive to said output signal of the radio receiver, whereby said flares are ignited in response to the received signal from the remote source.

2. An aerial tow target comprising a hollow thin-walled rigid body member having a low drag aerodynamic configuration, the walls of said body member being formed of a non-metallic material permeable by radar waves, means defining a plurality of normally intersecting planes interiorly of said body member and having a metallic surface for reecting exteriorly propagated radar waves, a rearwardly directed flare magazine in the trailing end of said body member; a plurality of rearwardly directed flares mounted in said magazine; a radio receiver carried within said body member, said radio receiver developing an output signal in response to a received signal from a remote source; means for igniting said flares in sequence including means responsive to said output signal of the radio receiver whereby said flares are ignited in response to the received signal from the remote source; a plurality of fin elements carried by the trailing portion of said body member for stabilizing the same in towed night; said fins being formed of a non-metallic material; and elements embedded within said n elements forming an antenna for said radio receiver.

3. An aerial tow target for practice in the detection of self-propelled aerial objects, comprising: a streamlined body; means carried by the leading end of said body for connection to a tow cable whereby said target may be towed by an aircraft to which said cable is affixed; a rearwardly directed flare holder mounted to the trailing end portion of said streamlined body; at least one rearwardly directed flare mounted in said holder; a radio receiver carried within the body of the tow target, said radio receiver developing an output signal in response to a signal received from a remote signal-generating source; and means for igniting said are, including means responsive to said output signal of the radio receiver, whereby said Hare is ignited in response to the received signal from the remote signal-generating source during the tow of the target.

4. An aerial tow target, comprising: an elongate, streamlined body member for connection to a tow cable for tow by an aircraft to which said cable is afxed; a rearwardly directed liare holder mounted to the trailing end of said body member; a rearwardly directed flare mounted in said holder; a radio receiver carried within said ybody member, said radio receiver responsive to a received signal from a remote source for developing an output signal; an electromotive source carried by said body member; electro-responsive means carried Within said body member for igniting said flare; and means responsive to the output signal of said radio receiver for electrically coupling said electromotive source to said electro-responsive ignition means for actuation of the same, thereby to ignite said are in response to the received signal from the remote source.

5. An aerial tow target for practice in the detection of self-propelled aerial objects, comprising: a streamlined body for connection to a tow cable; at least one charge of rapidly combustible material carried by said lbody to create a highly visible flame; remotely controlled ignition means on said body to ignite said charge; means for supporting said body on an aircraft for transportation to a practice area; and safety means to make said ignition means inoperative in response to engagement of the body by said supporting means.

6. An aerial tow target for practice in the detection of self-propelled aerial objects, comprising: a streamlined body for connection to a tow cable; at least one charge of rapidly combustible material carried by said body to create a highly visible flame; a radio receiver carried by said body; an electromotive source carried by said body; electrical means to ignite said charge; means responsive to said radio receiver to place said source in electrical communication with said ignition means; means for supporting said body on an aircraft for transportation to a practice area; and safety switch means responsive to engagement of the body by said supporting means to render said igniting means inoperative.

7. An aerial tow target for practice in the detection of self-propelled aerial objects, comprising: a streamlined body for connection to a tow cable; at least one charge of rapidly combustible'material carried by said body to create a highly visible ame; a radio receiver carried by said body; an electromotive source carried by said body; electrical means to ignite said charge; means responsive to said radio receiver to place said source in electrical communication with said ignition means; safety switch means to make said igniting means inoperative when the tow target is on the ground; and a safety operating member for insertion into said body to actuate said safety switch means.

8. A combination as set forth in claim 7, which includes an audio jack to permit a headphone set to be plugged into said radio receiver for tuning the radio Ieceiver; and which includes normally open switch means responsive to the plugging in of the headphone set to turn on the radio receiver.

References Cited in the le of this patent UNITED STATES PATENTS 2,342,651 Dircksen Feb. 29, 1944 2,419,549 Griesinger Apr. 29, 1947 2,463,517 Chromak Mar. 8, 1949 2,499,012 Welsh Feb. 28, 1950 FOREIGN PATENTS 737,318 Great Britain sept.' 21, 1955 

